Stability of the ANAMMOX process in a gas-lift reactor and a SBR

In the last years, the ANAerobic AMMonium OXidation (ANAMMOX) process has been put forward as a promising alternative to treat ammonium rich wastewaters. An ANAMMOX gas-lift reactor and a sequential batch reactor (SBR) were operated during around 200 days in this study, reaching nitrogen loading rates (NLRs) of 2.0 and 0.75 g l(-1) per day, respectively. The efficiency in the nitrite (limiting substrate) removal was 99%. The ammonium and nitrite influent concentrations were increased stepwise until biomass in the reactors started to float. These flotation events coincided with periods when the NLR exceeded the maximum specific ANAMMOX activity (MSAA) of the sludge. The MSAA, determined in batch experiments, was 0.9 and 0.44 g g(-1) per day for biomasses from the gas-lift reactor and the SBR, respectively. Flotation of the biomass occurred most likely due to a granule density decrease caused by dinitrogen gas accumulation inside the granules and an apparent breakage of the granules. Further research is needed to understand this phenomenon and to optimise the corresponding strategies to counteract the location. (C) 2004 Elsevier B.V. All rights reserved

Evaluation of activity and inhibition effects on Anammox process by batch tests based on the nitrogen-gas production

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Enrichment of Anammox biomass from municipal activated sludge: experimental and modelling results

Contains fulltext : 60390.pdf (publisher's version ) (Closed access)Anaerobic Ammonia Oxidising (Anammox) biomass was enriched from sludge collected at a municipal wastewater treatment plant, employing a Sequential Batch Reactor (SBR). After 60 days Anammox activity started to be detected, by consumption of stoichiometric amounts of NO2- and NH4+ in the system. Fluorescence In Situ Hybridisation analysis confirmed the increase of Anammox bacteria concentration with time. A final concentration of enriched biomass of 3-3.5 gVSS dm(-3) was obtained, showing a Specific Anammox Activity of 0.18 gNH(4)(+)-N gVSS(-1) d(-1) The reactor was able to treat nitrogen loading rates of up to 1.4 kgN m(-3) d(-1), achieving a removal efficiency of 82%. On the other hand, the start-up and operation of the Anammox SBR reactor were consequentially modelled with the Activated Sludge Model nr 1, extended for Anammox. The simulations predicted quite well the experimental data in relation to the concentrations of nitrogenous compounds and can be used to estimate the evolution of Anammox and heterotrophic biomass in the reactor. These simulations reveal that heterotrophs still remain in the system after the start-up of the reactor and can protect the Anammox microorganisms from a negative effect of the oxygen. (C) 2004 Society of Chemical Industry